I have been seeing this concept of Twice NAT on cisco devices and Double NAT on Checkpoint devices. Somehow I am not able to understand how they work. Are they the same? Could anyone please explain whaht these concepts actually achieve?
I am mainly looking for an example where the destination also changes.
You are right that twice NAT simply means that both the source and the destination IP addresses in the packet are translated. In the new NAT syntax of ASA 8.3 and 8.4, you can do this in a single command:
With this example, if a packet sourced from 10.1.1.1 and destined to 192.168.1.1 arrives at the inside interface, the ASA will translate the source address to the outside interface IP. It will also translate the destination address to 172.16.1.1.
Traffic will get initiated from 10.1.1.1 and the ultimate destination will be 172.16.1.1 (translated destination address). The source address (10.1.1.1) will get hide natted to the interface address. The translated destination address (172.16.1.1) will get translated to the external destination (192.168.1.1). so the traffic is like this
1. SA: 10.1.1.1 DA: 172.16.1.1
After the traffic leaves the outside interface
2. SA: Firewall Interface address DA: 192.168.1.1
Return traffic from 192.168.1.1 will get natted back to 172.16.1.1 once it reaches the firewall
We have configured the outside and inside Interface with official ipv6 adresses, set a default route on outside Interface to our router, we also have definied a rule , which also gets hits, to permit tcp from inside Interface to any6.
In Syslog I also se...